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Browsing by Author "Dorr, Brian S."

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    Distribution and abundance of scaup using baitfish and sportfish farms in eastern Arkansas
    Clements, Stephen A.; Dorr, Brian S.; Davis, J. Brian; Roy, Luke A.; Engle, Carole R.; Hanson-Dorr, Katie C.; Kelly, Anita M. (2020-11)
    Arkansas' bait- and sportfish facilities are commonly used by various piscivorous bird species, including lesser scaup (Aythya affinis) and greater scaup (A. marila) that consume substantial quantities of fish. To mediate this predation, farmers implement extensive bird harassment programs that create additional costs to fish loss, thus research investigating the distribution and abundance of scaup is needed to help farmers allocate their bird harassment efforts more efficiently. In winters 2016-2017 and 2017-2018 we conducted 1,368 pond surveys to investigate pond use by scaup on farms during birds' regular wintering period (i.e., November-March). We used intrinsic and extrinsic pond-level and farm-level characteristics as explanatory variables in generalized linear models to reveal characteristics associated with increased scaup use. Inter-annual differences in scaup use were also considered in each model. Our pond-level model showed that scaup occurred more frequently on larger golden shiner (Notemigonus crysoleucas) and fathead minnow (Pimephales promelas) ponds stocked at greater densities, particularly during our second study winter. Our farm-level model suggested that farms further from major rivers and with an average pond size of approximately eight hectares had the greatest probability of scaup use. Producers can apply findings from our models to implement bird harassment efforts in times and locations where scaup predation is more likely to occur.
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    Scaup Depredation on Arkansas Baitfish and Sportfish Aquaculture
    Clements, Stephen A.; Dorr, Brian S.; Davis, J. Brian; Roy, Luke A.; Engle, Carole R.; Hanson-Dorr, Katie C.; Kelly, Anita M. (2021-09)
    Lesser scaup (Aythya affinis) and greater scaup (A. marila), hereafter scaup, consume a variety of aquatic invertebrates, plants, and occasionally small fish. Scaup have foraged on commercial aquaculture farms in the southern United States for decades. However, the types, abundance, and rate of fish exploitation by scaup on baitfish and sportfish farms are not well documented. Thus, information is needed to understand how fish and other foods influence scaup use of aquatic resources, and any potential economic effects of depredation of fish. From November-March in winters 2016-2017 and 2017-2018, we conducted 1,458 pond surveys to estimate the abundance and distribution of scaup on Arkansas baitfish and sportfish farms that commercially produce species such as golden shiners (Notemigonus crysoleucas), fathead minnows (Pimephales promelas), goldfish (Carassius auratus), and sunfish (Lepomis spp.). We also collected and processed 531 foraging scaup and quantified the proportion of scaup consuming fish and the proportion of their diet obtained from fish. Fish consumption was highly variable between years. In our survey area, we estimated total fish consumption at 1,400 kg and 60,500 kg for winters 2016-2017 and 2017-2018, respectively. Sunfish ponds experienced the maximum loss (18,000 fish/ha) during winter 2017-2018, while goldfish ponds experienced a loss of just 2,600 fish/ha during the same winter. The estimates of baitfish and sportfish loss to scaup revealed potential management strategies for minimizing fish loss and can inform economic analysis of the financial impact of scaup on producers. (c) 2021 The Wildlife Society.